One in 10 Adults Have a Food Allergy. Many More Say They Have One.

Many more Americans say they have a food allergy than actually have one.

Researchers surveyed 40,000 adults about food allergies, carefully eliciting details about which foods produced the allergies and what specific symptoms they had.

To be considered a true allergy, the person had to report at least one of the known symptoms of an immune system reaction to an allergen: hives, lip or tongue swelling, difficulty swallowing, throat tightening, chest tightening, trouble breathing, wheezing, vomiting, chest pain, rapid heartbeat, fainting or low blood pressure. An upset stomach, diarrhea or a report that “it makes my mouth itch,” for example, was considered evidence of a food sensitivity of some kind, but not the immune response produced by an allergy.

Using these criteria, the researchers estimated that 10.8 percent of American adults — or more than 26 million people — have an allergy to one or more foods. Another 21 million think they have a food allergy but do not. The report is in JAMA Network Open.

“With one in five adults having a negative reaction to a food, it is essential to see an allergist for a diagnosis,” said the lead author, Dr. Ruchi S. Gupta, a professor of pediatrics at Northwestern. “Food allergies can be life-threatening, but other food-related conditions may be treatable.”